HR: 1340h
AN: A53A-0856    [Abstracts]
TI: Regional Climate Model Downscaling of the U.S. Present Climate and Projected Change
AU: * Liang, X
EM: xliang@uiuc.edu
AF: Illinois State Water Survey, 2204 Griffith Dr, Champaign, IL 61820-7495 United States
AU: Kunkel, K E
EM: kkunkel@uiuc.edu
AF: Illinois State Water Survey, 2204 Griffith Dr, Champaign, IL 61820-7495 United States
AB: The MM5-based regional climate model (CMM5) simulations driven by the NCEP-DOE AMIP-II reanalysis and the integration of the NCAR Parallel Climate Model (PCM), an atmosphere-ocean coupled general circulation model (CGCM), for the present climate are inter-compared with observations to study the CMM5 downscaling skill and uncertainty. The result indicates that the CMM5, with its finer resolution and more detailed physics, simulates the present U.S. climate that is more accurate than the driving reanalysis and PCM output, especially for precipitation, including annual and diurnal cycles and daily variability. Hence, the CMM5 downscaling provides a credible tool to improve CGCM climate simulations. A parallel CMM5 run driven by the PCM future (2046-2050) projection is then compared to determine the downscaling impact on local-regional climate change. It is shown that the PCM-driven CMM5 generates very different patterns of U.S. climate change projections, with more spatially variable precipitation changes while smaller temperature increases than the PCM itself. This study suggests that the CMM5 downscaling can significantly reduce the uncertainty due to inadequate spatial resolution and incomplete physical representation of local and regional processes and hopefully the overall uncertainties among CGCMs.
DE: 3337 Numerical modeling and data assimilation
DE: 3309 Climatology (1620)
DE: 1854 Precipitation (3354)
DE: 1600 GLOBAL CHANGE (New category)
DE: 1610 Atmosphere (0315, 0325)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting